Speed ​​controller for grinder. Do-it-yourself grinder repair, from simple to complex Checking the start and control unit

For everyone who has been using the grinder for more than one year, it broke. At first, each master tried to repair the sparkling grinder on his own, hoping that it would work after replacing the brushes. Usually, after such an attempt, a broken tool remains lying on a shelf with burned-out windings. And a new grinder is bought to replace it.

Drills, screwdrivers, perforators, milling machines in without fail equipped with speed control. Some so-called calibration grinders are also equipped with a regulator, and ordinary grinders only have a power button.

Manufacturers do not deliberately complicate low-power angle grinders with additional circuits, because such a power tool should be cheap. It is clear, of course, that the service life of an inexpensive tool is always shorter than that of a more expensive professional one.

The simplest angle grinder can be upgraded so that the gearbox and armature winding wires will no longer be damaged. These troubles mainly occur during a sharp, in other words, shock start of the grinder.

All modernization is just assembly electronic circuit and fix it in the box. In a separate box, because there is very little space in the handle of the grinder.

A tested, working circuit is laid out below. It was originally intended to adjust the incandescence of lamps, that is, to work on an active load. Her main asset? simplicity.

1. The highlight of the soft starter, the schematic diagram of which you see, is the K1182PM1R chip. This microcircuit is highly specialized, of domestic production.
2. The acceleration time can be increased by choosing a larger capacitor C3. While this capacitor is being charged, the electric motor speeds up to maximum.
3. No need to replace the resistor R1 variable resistance. The 68 kΩ resistor is optimally matched for this circuit. With this setting, you can smoothly start the grinder with a power of 600 to 1500 watts.
4. If you are going to assemble a power regulator, then you need to replace the resistor R1 with a variable resistance. A resistance of 100 kΩ or more does not lower the output voltage. By short-circuiting the legs of the microcircuit, you can completely turn off the connected angle grinder.
5. By inserting a TS-122-25 semistor VS1 into the power circuit, that is, at 25A, you can smoothly start almost any grinder available for sale, with power from 600 to 2700 watts. And there is a large margin of power in case the grinder jams. To connect grinders with a power of up to 1500 W, imported seven-stores BT139, BT140 are enough. These less powerful electronic keys are cheaper.

The triac in the above circuit does not fully open, it cuts off about 15V of the mains voltage. Such a voltage drop does not affect the work of the grinder. But when the sevenstor is heated, the speed of the connected tool is greatly reduced. This problem is solved by installing a radiator.

This simple circuit has another drawback - its incompatibility with the speed controller installed in the tool.

The assembled circuit must be hidden in plastic boxes. The housing made of insulating material is important, because you need to protect yourself from mains voltage. You can buy a junction box at an electrical supply store.

A socket is screwed to the box and a cable with a plug is connected, which makes this design look like an extension cord.

If experience allows and there is a desire, you can assemble a more complex soft start circuit. Below circuit diagram is standard on the XS-12 module. This module is installed in the power tool at the factory.

If you need to change the speed of the connected electric motor, then the circuit becomes more complicated: a tuning resistor of 100 kOhm is installed, and a control resistor of 50 kOhm is installed. Or you can simply and roughly introduce a 470 kΩ variable between a 47 kΩ resistor and a diode.

In parallel with the capacitor C2, it is desirable to connect a resistor with a resistance of 1 MΩ (it is not shown in the diagram below).

The supply voltage of the LM358 chip is in the range from 5 to 35V. The voltage in the power circuit does not exceed 25V. Therefore, you can do without an additional zener diode DZ.

Whatever soft starter you build, never turn on the tool connected to it under load. Any smooth start you can burn if you hurry. Wait for the grinder to unwind, and then work.

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In the last article, I talked about how to connect and start a 380 Volt motor in a 220 V single-phase electrical network. Now I will talk about how to connect a single-phase electric motor from a broken washing machine, vacuum cleaner, etc. It can be successfully used for other purposes in household e.g. to drive a sharpener, polisher, lawn mower, etc.

Wiring diagram for a 220 Volt collector motor

AT electric drills, perforators, grinders and some models washing machines machines use a synchronous collector motor. It successfully starts and works in single-phase networks without unnecessary starting devices.

For, to connect the collector electric motor, it is necessary to connect with a jumper two ends No. 2 and No. 3, one coming from the armature, and the second from the stator. And connect the remaining 2 ends to a 220 volt power supply.

Remember that when connecting the collector an electric motor without an electronics unit, it will only work at maximum speed, and at startup there will be a strong jerk, high starting current, sparking on the collector.

It may be a 2-speed motor, then the 3 end from half of its winding will come out of the stator. When connected to it, the speed of rotation of the shaft will decrease, but this increases the risk of breaking the insulation when starting the motor.

To change the direction of rotation, it is necessary to swap the ends of the connection of the stator or armature.

Connection diagrams for single-phase asynchronous electric motors

If single-phase motors had only one winding in the stator, then the electromagnetic field inside it would be pulsating rather than rotating. And the launch would occur only after unwinding the shaft by hand. Therefore, for independent starting of asynchronous motors, an auxiliary or starting winding is added, in which the phase is shifted by 90 degrees with the help of a capacitor or inductance. The starting winding pushes the rotor of the electric motor at the moment of switching on. The main switching circuits are shown in the figure.

The first two circuits are designed to connect the starting winding for the duration of the motor start, but not more than 3 seconds in duration. For this, a relay or a start button is used, which must be pressed and held until the motor starts.

Even the most quality tool after some time it can break down, not to mention cheap "consumer goods". Bulgarian is also no exception. This tool has gained popularity due to its versatility and ease of use. Exists a large number of models of angle grinders, the device of which and the principle of operation do not differ significantly from each other. During operation, the tool may break. Repair in the workshop will come out in a tidy sum, so many craftsmen repair the grinder with their own hands.

Bulgarian device

Bulgarian in many cases is an indispensable thing. As with any other tool, it should be handled fairly carefully. In order to qualitatively repair the grinder with your own hands, you need to know how it works.

Anchor.

This part is located inside the electric motor and begins to rotate during operation. The higher the speed of its rotation, the more power the grinder has.

Collector.

It is a separate place of the armature, on which the control and power windings are located. With the help of the collector, signals are supplied to the control unit and the engine.

Electric brushes.

These elements used to supply current from power cable to the collector.

Reducer.

It is located in front of the grinder. Thanks to him, in the process of rotation, mechanical energy from anchor to disk.

It is one of the parts of the engine with an anchor located inside. This the detail in its design is the most complex, because all the windings are pressed very precisely in it.

In addition, the device of the tool includes its body, cable with a plug and handles-holders.

Before you start repairing the grinder with your own hands, it is best to have in front of you layout and wiring diagram and detailed instructions , which corresponds to a certain model. Do-it-yourself tool repair should be done with certain knowledge.

Bulgarian repair

When repairing any tool, they usually start with the simplest and end with the most complex. When repairing a grinder with their own hands, they also adhere to this rule.

There are situations when the tool stops working and does not turn on. The reason for this most often lies in the fact that the brushes cease to flow electricity. The whole problem in this case will be either in the wire or in the plug, or the trigger will simply break. Troubleshooting you should disassemble the grinder and check that there are no breaks in the cable. As soon as the wire is replaced, the tool starts to work normally.

The grinder does not work, but the wire and plug are not damaged. In this case, instead of do-it-yourself repair, it will consist in dismantling the trigger mechanism. All items to be removed must be marked. This is done so that you can later assemble it correctly. Otherwise, the armature may jam or the winding may burn out. trigger brushes, you can pick up any similar button.

If the trigger and wire are OK, but the tool still does not work, then the problem is most likely in the brush holders. Usually, for a spark to appear and start the mechanism, it is necessary to clean the contact plates. In case of failure, the existing solder should be replaced. They usually run smoothly for about two years. It should be noted that some models of grinders have a brush connection. In this case, soldering and installing new ones should only be in the kit. Partial replacement is not possible.

After replacing the old ones with new ones, you need to carefully examine them. If uneven wear is quite serious, it means that the moving part of the grinder or the center of gravity has shifted. In this situation should consult a specialist, because it is almost impossible to fix the malfunction and adjust the center of gravity with your own hands.

More specific faults, the repair of which requires gear skills and knowledge, are:

• jamming of bearings;
• failure of the control electronics;
• body deformation;
• breakage of gear casing teeth;
• failure of the stator or armature;
• collector failure.

If there are mechanical defects in the grinder, then more attention should be paid to the condition of the large gear, shank and bushings. If uneven wear of the shafts or teeth is found, then it is necessary to replace the worn parts as soon as possible.

Operating rules

In order to avoid repairing the grinder with your own hands, you must observe the following important rules operation.

To date, the stores have a very large selection of power tools. All of them differ both in price and in functionality and reliability. Almost everyone modern models electric drills, jigsaws, screwdrivers have a speed controller. But grinders with such an opportunity are very rare, and if they exist, they are much more expensive. In order not to overpay too much, I decided to equip my grinder bought long ago. In principle, a regulator is not needed for cutting metal with a cutting stone, but for grinding cases in amateur radio practice he just can't be replaced.

Schematic diagram of the grinder speed controller

So, the controller circuit. It is very simple, and there is a topic on our forum to discuss it. Even for a beginner radio amateur, it will not be difficult to assemble it. Parts are not expensive, and you can easily buy them in a store, or solder them from old boards (if they are there, of course). Can also be assembled separately in a box with a socket. Then use it as a carrier with a power regulator. For a while I was like that. After I got tired of competing with carriers, and I assembled the regulator in the handle of the grinder.

First you need to collect all the details in a bunch. Unscrew the handle of the grinder, and consider the location of each element of the circuit. AT different brands grinders have different handles, and how you place everything there, and indeed, whether everything will fit in there is already your concern. In extreme cases, you can collect in a separate box.

Radiator cut from a piece of aluminum. A triac was attached to it. By the way, it does not get very hot during operation, so the radiator can be made with small area. Then I soldered all the parts by surface mounting according to the diagram.

So that during work this whole thing does not shake and short-circuit - glued epoxy resin. Variable resistor installed on the other side. He put on a large plastic handle. Even when working with it, it is convenient to change the speed of the grinding wheel.

The famous Japanese brand Makita enjoys well-deserved popularity among consumers around the world. All Makita brand products stand out for their high quality, ergonomics, and affordable prices. And a competent Russian consumer tries to squeeze more out of the tool than it can give. Makita angle grinders have their own ultimate strength.

Do-it-yourself repair of the Makita angle grinder is not particularly difficult and can be done as in service center, and independently, since you can freely purchase the necessary spare parts. Malfunctions of the angle grinder and how to eliminate them are discussed in detail in the attached instructions.

Design features grinder Makita

Bulgarian is an angle grinder, which received such a name only in the open spaces former USSR. Structurally, any angle grinder (angle grinder) has the same structure.

The principle of operation of Makita angle grinders is based on the conversion of electrical energy into mechanical energy. This leads to the rotation of the shaft, on which the disc for cutting, grinding, polishing is installed. And it is called angular for the reason that in the gearbox used, the torque is transmitted at an angle of 90º.

Since the cooling of the electric motor in the Makita angle grinders is provided by the suction of external air through the ventilation holes, the working parts of the Makita angle grinders are covered with a special protective powder varnish that prevents dust from settling. Structurally, Makita grinders are provided with a labyrinth system of seals and the Start button is sealed.

But each company introduces its own zest into the design to attract a buyer. The grinder Makita is not deprived of this either. Bulgarians Makita are conditionally divided into powerful and small.

Bulgarians Makita are marked depending on the power of the electric motor.

To design features Makita angle grinders include:

• The presence of a labyrinth device that protects the bearings from dirt and dust.
• The windings of the electric motor in the grinders of high power are protected by an armored coating.
• Makita angle grinders are equipped with a special system that protects the tool from jerking when starting, called the Super-Joint-System.

A few words about the SJS system. The system prevents kickback, eliminates jerks and jamming of the working body, protects the electric motor from overloads.

The system uses a spring, the purpose of which is to transfer forces from the rotor to the gears of the gearbox. The spring acts as a buffer, preventing jerks when starting and stopping. This design greatly reduces vibration and ensures smooth operation of the Makita angle grinder.

Makita Bulgarians are divided into classes according to the width of the working disk. Bulgarians are conditionally divided into three classes: light, medium, heavy. In turn, each class is divided into grinders for professionals and for domestic needs. At professional models angle grinders Makita increased power reserve, integrated security system, increased working life. Professional angle grinders perfectly withstand heavy loads for a long time.

Makita household angle grinders have high performance characteristics but very reasonable prices. For Makita grinders, a disc with a maximum diameter of 230 mm can be used.

Depending on the diameter of the disk, Makita angle grinders are divided into classes:

• Diameter 115-125 mm characterizes light class. Easily held with one hand by the body, which acts as a handle. But professional angle grinders of this class can be equipped with a rear handle, which has a built-in power button for the tool;
• A diameter of 150-180 mm refers the Makita grinder to the middle class. AT this category includes professional and amateur models equipped with electric motors of various capacities. Modern models have a swivel rear handle;
• The diameter of 230 mm characterizes the heavy class grinders. In this class, Makita grinders are produced exclusively for professionals. These machines are designed to work on concrete, stones, bricks, etc. Everything is included in their design. modern systems protect the user from injury.

Makita grinder models are available for discs with diameters of 115 mm, 125 mm, 150 mm, 180 mm and 230 m.

In grinders of high power, it is possible to replace carbon brushes without removing the stator housing cover.

Makita Bulgarians of various capacities differ in appearance. Professional grinders with a power of over 1000 W have a large body and a comfortable rear handle. The handle is equipped with protective anti-vibration pads in black. Bulgarians with a power of up to 1000 W have a convenient body, which acts as a handle.

Makita angle grinders have a quick-release cover. This design allows you to quickly remove the protective cover.

Tool required for repair

Do-it-yourself repair of Makita angle grinders requires the use of a specific tool. Not without a set of screwdrivers. It is preferable that they be equipped with a ratchet mechanism. The best option use a cordless screwdriver. To repair the electrical part of the Bulgarian Makita, you will need a tester, a device for determining short-circuited turns IK-2. And also prepare an open-end wrench, bearing pullers, a hammer, a soft metal tip. Well, you can not do without the necessary lubricants , cleaning materials, liquids for washing off old grease.

It is necessary to start repairing an angle grinder with your own hands by preparing the workplace, installing the right lighting. You will need a diagram of the angle grinder of the desired model and the proposed instructions.

Any malfunctions of power tools are divided into two types: electrical and mechanical.

We will consider the repair of units of the grinder Makita using the example angle grinder diagrams Makita 9565.

Possible electrical faults

Makita grinder electrical malfunctions can be divided into control circuit malfunctions, rotor failure and stator failure.

How to troubleshoot the Makita grinder control circuits

If your grinder Makita does not turn on, the biggest reason there may be a breakdown in the power and control circuits.

To get to the components of the control circuits, it is necessary to remove the rear cover of the housing pos.38 by unscrewing the self-tapping screw 4×18 pos.39. Switch ST115-40 K9565 poz.28 is mounted in the switch holder poz.27. The switch holder is closed with a cover poz.29, which is attached to the motor housing poz.33.

The power cable poz.37 is suitable for the switch. Using a tester, check the continuity of the circuits from the plug contact to the switch terminals. The switch poz.28 is controlled by the lever poz.30. From the switch contacts, check the circuit to the carbon brushes poz.42.

In control circuits, the weakest link is the carbon brushes. The angle grinder Makita 9565 uses carbon brushes CB-318 with auto-off, so check the brushes.

In professional angle grinders, speed controllers are installed. In grinders Makita with a power of more than 1000 W, the installation of a soft start system is provided. The Makita 9077SF angle grinder is equipped with such a system.

If the switch fails, the malfunction is eliminated by its complete replacement. If the power supply wire is broken or broken, the malfunction is eliminated by replacing the entire wire or removing its damaged parts.

The switching process is carried out using the lever poz.30. If you disassembled the grinder body for repair or maintenance, lubricate the lever movement grooves with silicone grease before reassembly.

Checking the electric motor

In addition to the control circuits, the electric circuit of the angle grinder includes a rotor and a stator. These are complex units, the repair of which is recommended to be carried out in specialized centers. But for Russian craftsmen there is nothing inaccessible. We recommend ours.

How to repair the stator grinder Makita

The failure of the stator, position 24, of the angle grinder is indicated by the appearance of a burning smell, overheating of the grinder body, and a spontaneous set of revolutions of the grinder. In the body of the angle grinder pos.33, the stator is fastened with four self-cutting screws 4 × 70 pos.21. To prevent damage, the stator is closed by protection poz.20.

Repair of the stator grinder Makita consists in determining a short circuit or open windings. It is best to perform stator diagnostics with a special device called IK-2. The stator is considered faulty if traces of darkening of the winding are visible, a break is detected or short circuit winding turns.

Just. We need to rewind its windings.

How to repair the rotor grinder Makita

In case of overheating of the grinder, the appearance of a burning smell, an increase in sparking in the area of ​​\u200b\u200bthe collector, it is necessary to pay attention to the integrity of the rotor pos.13.

Scheme grinder Makita

The dismantling of the rotor is associated with sequential disassembly. To remove the rotor, it must be released from the gearbox pos.3. To do this, unscrew the hex nut M6 pos.4. To unscrew the nut, you need to clamp the rotor with one hand. With the other hand, with open end wrench, unscrew the nut counterclockwise.

Remove the nut, pull out the flat washer pos.5, remove the spiral bevel gear pos.6, remove the retaining spring pos.7. Swinging the rotor to the sides, carefully pull it out of the gearbox housing pos.3. After removing the retaining ring pos.8, use a puller to pull the bearing pos.9.

The Makita 9565 grinder uses a 6001LLB bearing.

It remains to remove the flat washer pos.10 and the gearbox cover pos.11.

in front of you appearance grinder rotor Makita 9565 with an insulating washer pos.14, a flat washer 7 pos.15, a bearing pos.16 and a rubber boot 22 pos.17. In the angle grinder, a 627zz bearing is used on the collector side. Russian analogue 80027.

Rotor repair consists in replacing it with a new or repaired one. You can repair the rotor yourself, but you need not only patience, equipment, material. This is a high class job.

Mechanical damage

In addition to the electrical part, the grinder also includes a mechanical part, the main unit of which is the gearbox.

How to repair the grinder gearbox

The gearbox consists of a housing, driving and driven gears. The drive gear is put on the rotor shaft. The driven gear is attached to the spindle poz.50.

On the grinder Makita 9565, the driven gear is pressed onto the spindle. And in the grinder model Makita 9558HN, the driven gear is mounted on the shaft with a keyway.

Reducer failures are associated with the failure of the gear teeth. Gears are licked or some of the teeth are chipped.

Repair gearbox grinder Makita is to replace a pair of helical gears. Gears are replaced only in pairs.

To remove the driven gear, you can not do without a press or a special puller. Do not use a hammer as the gearbox housing is made of fragile material.

Assembling grinder Makita 9565

Before assembling the Makita grinder, check the integrity of all parts and their cleanliness. The assembly begins with the installation of the bearing and the driven gear on the spindle.

Spindle Assembly

Anther poz.51 is put on the spindle poz.50, the housing cover poz.53, the bearing housing poz.54. Insert a pre-lubricated 6201LLB bearing into the bearing housing. Press the driven gear poz.56. on the spindle. Spindle assembled.

Installing the rotor in the gearbox housing

Insert a repaired or new rotor with bearings on into the gearbox housing, put on all the parts according to the drawing, fit the drive gear and fix it with a nut.

In the process of installing the rotor in the gearbox housing, control the pressing of the bearing. A properly installed rotor turns easily in the gearbox housing.

Installation of the rotor in the stator housing

An assembled gearbox with a rotor is inserted into the stator housing, on which the bearing is pressed from the side of the collector, closed with a protective rubber boot, and the ease of scrolling is checked. It remains to install the assembled spindle in the gearbox housing.

Insert the assembled spindle into the gearbox housing pos.3, after laying the rubber ring pos.55 and lubricating the bolts pos.52 with sealant.
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All operations for assembling the mechanical part of the grinder are accompanied by mandatory parts. Special attention pay attention to the process of applying lubricant to the grinder gearbox.

Here it is important not only its quality, but also quantity. Lubrication in the amount of 1/3 of the volume of the gearbox is placed in the gearbox housing of the angle grinder.

Having assembled the mechanical part of the grinder, each time before tightening the fixing screws, check the ease of rotation of the gearbox by turning it by the spindle.

At the final stage, it remains to install the carbon brushes, put on the back cover of the case and check the tool's performance.

Makita 9565 grinders are equipped with CB-325 carbon brushes. Timely replacement of carbon brushes will not only save the rotor, but also extend the life of the entire tool.

As a rule, carbon brushes are changed after 7000 hours of operation or when worn up to 8 mm in length. In ec strange cases can be used. But at the first opportunity it is necessary to establish relatives.

If your grinder after assembly works without extraneous noise, without jerks, you can be congratulated. The task of repairing the grinder Makita has been completed.